1. Field of the Invention
Embodiments of the present invention generally relate to solid state lighting systems and, more particularly, to interchangeable light modules having replaceable solid state light emitters.
2. Description of the Related Art
Advances in light-emitting diode (LED) luminous efficiency are allowing solid state emitters into numerous lighting applications that were previously unavailable. Solid state lighting is even replacing incandescent lighting technology in some applications where increased reliability is desired, especially in harsher environments where vibrations may occur (e.g., automobile taillights).
However, the lifetime of an LED is dependent on the junction temperature, and the junction temperature is proportional to forward current. To approach the luminous intensity of other lighting technologies, LEDs may need to operated at relatively high forward currents (e.g., in the hundreds of milliamps), thereby increasing the junction temperature. Since most LED semiconductor layers are formed on substrates of silicon, sapphire, or silicon carbide (SiC), the LEDs do not effectively conduct heat away from the LED die. To counteract this effect as shown in FIG. 1, a solid state emitter 100 may be mounted on a heat sink 102, typically by soldering the leads 104 of the emitter 100 to the heat sink 102. The heat sink 102 dissipates heat away from the LED die of the solid state emitter 100 and generally reduces the junction temperature of the LED die. Another example of this may be shown in the solid state light array 200 of FIG. 2, where several solid state light emitters 202 have been reflowed or soldered to a metal core printed circuit board (MCPCB) 204 functioning as a heat sink.
Large heat sinks may present problems for solid state light structures utilizing them. The benefit of increased heat dissipation from large heat sinks translates into higher soldering or reflow temperatures when the solid state light emitters need to be connected or disconnected from a mounting, such as a printed circuit board (PCB) or an MCPCB. These increased desoldering temperatures oftentimes hinder removal of a failed light emitter from a PCB in the field using a soldering iron and may lead to damage to the PCB during a light emitter replacement operation. Furthermore, a large heat sink may prevent a solid state light structure from entering an application where a smaller size is necessary. This problem is compounded when multiple solid state light emitters are necessary on a single light structure, and the spacing between light emitters is increased for proper heat dissipation capability of the heat sink (see FIG. 2).
Accordingly, what is needed is an improved solid state light structure for use in a solid state lighting system.